1. Field of the Invention
The present invention relates to overvoltage surge arresters having thermally sensitive fusible fail short protection associated therewith, and more particularly, a solid state surge protector with a thermally sensitive fusible fail short protection enclosed in an assembly, which is the same in size as a three terminal gas tube arrestor and may readily replace same.
2. Background of the Invention
Although thermally sensitive fusible fail short protection has been associated with overvoltage gas tube protectors for a long time and are well known in the art. They are presently used extensively for telephone communication systems and have been steadily included with solid state devices, which are more reliable. The size of the solid state device has not been critical and they have been, generally speaking, larger in size than the gas tube arresters. At the present time, there appears to be a concentrated effort to reduce the size of all types of electronic equipment. Therefore, the solid state overvoltage surge protector, being in wide use, became the subject of a concentrated effort to reduce its size. Many attempts have been made to provide a package, which may readily replace the gas tube arrestor with its associated thermally sensitive fusible fail short protection in a miniature assembly, which may be directly inserted in the same mounting that was used for the gas tube arrestor.
One assembly, which attempts to utilize a miniaturized solid state overvoltage protection device is disclosed in U.S. Pat. No. 5,224,012, issued to Thomas J. Smith on Jun. 29, 1993. Disclosed therein is a miniature solid state surge protector apparatus for use on telephone central offices or the like, which does not include a thermally sensitive fusible fail short protection associated therewith. This configuration is not suitable for direct replacement of the present gas filled overvoltage surge arrestor. Therefore, it is an object of the present invention to provide a miniaturized solid state overvoltage protection device having thermally sensitive fusible surge protection associated therewith in an assembly which is readily substituted for a present gas tube overvoltage protection device.
It is another object of the present invention to provide a overvoltage protection device having three terminals, which is a direct replacement for a three terminal gas tube overvoltage protection device.
It is yet another object of the present invention to provide a solid state overvoltage protection device including thermally sensitive fusible surge arresters which are disposed in a three terminal device readily mountable and easily replaceable in the same volume as the present gas filled surge arrestor.